A Comparison of Two Techniques for Determining Glomerular Size Distributions in Domestic Fowl

Abstract

Nephrons in the avian kidney have an extremely heterogeneous size distribution. The shortest nephrons have very small glomeruli, and the larger nephrons have very large glomeruli. Physiological, nutritional, and disease factors may be correlated with the functioning of different sized nephrons. The present study was conducted to compare two techniques for measuring glomerular size distributions. A postmortem India ink infusion technique gave results that were highly comparable to an in vivo alcian blue infusion technique. Single Comb White Leghorn pullets were found to have approximately 270,000 glomeruli per kidney; glomerular circumferences and diameters ranged between .07 to .42 mm and .02 to.14 mm, respectively. A unimodal size distribution was found, with most glomeruli falling within the circumference range of .15 to .26 mm. The alcian blue technique should provide a quantitative in vivo method for evaluating selective tubular damage or physiological glomerular intermittency.

Kidney Function in Domestic Fowl with Chronic Occlusion of the Ureter and Caudal Renal Vein

“…The glomerular size distribution pattern for the control group (Figure 3) is in close agreement with patterns published previously (Niznik et al, 1985;Unflat et al, 1985). The pattern for the clamp group was unexpected in three respects.…”

“…The blood was centrifuged immediately and plasma osmolalities were measured (Wescor 5100C Vapor Pressure Osmometer); remaining plasma was stored frozen. After the final urine collection, alcian blue was infused into the brachial cannulas of birds in the control and clamp groups, as described previously for determining glomerular size distributions (Niznik et al, 1985;Unflat et al, 1985). Finally, birds were euthanized with an intracarotid injection of 20% urethane.…”

Liquid Methionine Hydroxy Analog (Free Acid) and DL-Methionine Attenuate Calcium-Induced Kidney Damage in Domestic Fowl

“…The initial damage caused by excess Ca or IBV presumably involves the direct destruction or mineralization of individual nephrons or obstructive degeneration of small groups of nephrons due to focal blockage of the urinary system by microscopic uroliths. When alcian blue is infused intravenously, the functioning glomeruli are stained so that morphometric techniques can be used to calculate their overall number and size distributions, thereby quantifying any microscopic or "hidden" kidney damage caused by excess dietary Ca or IBV (Niznik et al, 1985;Unflat et al, 1985;Cowen et al, 1987b;Wideman and Cowen, 1987). Exposing young pullets to IBV or excess dietary Ca at 4 to 8 wk of age when new nephrons still were developing from embryonic foci (Wideman, 1989) significantly reduced the number of functioning glomeruli (Niznik et al, 1985;Wideman and Cowen, 1987).…”

Glomerular size and volume distributions for cranial, medial, and caudal divisions of domestic fowl kidneys

“…The functional component of this assumption cannot be tested directly using intact kidneys, although extensive control studies have shown that model caudal kidney divisions function essentially normally when compared with control kidneys on a per gram kidney weight basis (Wideman and Gregg, 1988;Vena et al, 1990;Gregg and Wideman, 1990). Anatomical comparisons of the separate kidney divisions can readily be accomplished using glomerular size and volume distributions as a quantitative index for evaluation (Unflat et al, 1985;Wideman, 1989). This technique has been used previously to relate differences in nephron numbers and glomerular sizes to changes associated with maturation, genetics, nutrition, ureteral obstruction, compensatory hypertrophy, renal hemodynamics, and renal disease (Niznik et al, 1985;Wideman et al, 1985Wideman and Laverty, 1986;Wideman and Cowen, 1987;Roush and Spotts, 1988;Wideman, 1989;Gregg and Wideman, 1990;Vena et al, 1990).…”